Machining tool heads employing cross-feed slides are conventionally dynamically balanced through use of equal and opposite tool blocks mounted on cross slides effecting simultaneously radial feed of cutters mounted thereon. When the cross slides are in their extreme outermost position, normally at the start of the operation, and with the head rotating at high speed, resulting centrifugal force on the individual tool blocks must be overcome to feed the blocks radially inward. With a central draw bar, such as one actuated through crank linkage to simultaneously feed the tool blocks radially inward, the draw bar force involved has limited feasible rotational speeds and head diameters from those which could otherwise be employed. Excessive power for actuating the draw bar may otherwise be required which may be unavailable or cause damage or excessive wear to the actuating linkage.
If the slide were constructed with a fixed counterweight effective to substantially reduce the net centrifugal force resisting inward feed, a problem of weight shift across the centerline and frequently resulting tool mark would result when the radially inward movement of the tool block progresses beyond the balance point of relative centrifugal forces.